# Regions establish a new block formatting context.
# ...
# Floats or other exclusions potentially impact content laid out in regions,
# just as for non-regions. In the following example, the inline content coming
# from the body_text named flow wraps around the #float box.
As Anton notes in [1], you can't have regions establish a new block formatting
context *and* have floats outside them impact the content inside. This amounts
to specifying exactly opposite things. (The inline content of a block formatting
context root pretty much by definition is not impacted by floats outside it.)
[1] http://lists.w3.org/Archives/Public/www-style/2011Jul/0158.html
~fantasai